Back contact cell, back contact cell string, cell assembly, and photovoltaic system

Abstract

The invention relates to the technical field of solar cells, and particularly discloses a back contact cell, a back contact cell string, a cell assembly and a photovoltaic system.The back contact cell comprises first grid lines and second grid lines which are alternately arranged in the first direction; the first Pad points and the second Pad points are alternately arranged in the second direction, the first Pad points are connected with the first grid lines, and the second Pad points are connected with the second grid lines; wherein the first grid line comprises a first grid line body and a third grid line, and the first grid line body and the third grid line are connected into an integrated structure; along the first direction, the third grid line is arranged at the corresponding first pad point, and the width of the third grid line is greater than that of the first grid line body. The problem of welding tension in the prior art can be solved, and the connection reliability between the welding strip and the fine grid is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a back-contact cell, a back-contact cell string, a cell assembly, and a photovoltaic system. Background Art

[0002] A back-contact solar cell is a cell in which both the emitter and base contact electrodes are placed on the back side of the cell (non-light-receiving side). The light-receiving side of the cell is not blocked by any metal electrode, which effectively increases the short-circuit current of the cell. At the same time, the back side can allow for wider metal grid lines to reduce the series resistance and thus increase the fill factor. This type of cell with no obstruction on the front side not only has a high conversion efficiency, but also looks more beautiful. At the same time, components with full back electrodes are easier to assemble.

[0003] In order to improve the photoelectric conversion efficiency of the back-contact solar cell, the back-contact solar cell adopts a busbar-free design. The busbar-free back-contact cell refers to a secondary grid with two polarities that are staggered and distributed on the back of the cell, and the traditional busbar design is eliminated. Due to the elimination of the busbar, the busbar-free back-contact cell can improve the energy density, and the busbar-free back-contact cell significantly improves the photoelectric conversion efficiency of the cell by reducing shading loss and optimizing the electrode layout.

[0004] However, on the one hand, in such a technical solution, due to the main grid-free design on the back side, the connection reliability between the welding strip and the fine grid is poor, and the pulling force on the fine grid during welding is large, which can easily cause the grid to break; on the other hand, it is difficult to perform hot spot, EL and other performance tests on the back-contact solar cells. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a back contact battery, aiming to solve the welding tension problem in the prior art and improve the connection reliability between the welding strip and the fine grid.

[0006] The technical problem to be solved by the present invention is also to provide a back-contact cell that can efficiently and conveniently perform hot spot, EL and other performance tests on the back-contact solar cell.

[0007] The technical problem to be solved by the present invention is also to provide a back-contact battery string, a battery assembly and a photovoltaic system.

[0008] In order to solve the above problems, the present invention provides a back contact battery, comprising:

[0009] First grid lines and second grid lines are alternately arranged along a first direction;

[0010] A first Pad point and a second Pad point are alternately arranged along a second direction, wherein the first Pad point is connected to a first gate line, and the second Pad point is connected to a second gate line;

[0011] Wherein, the first gate line comprises a first gate line body and a third gate line, and the first gate line body and the third gate line are connected into an integrated structure;

[0012] Along the first direction, the third gate line is arranged at a position corresponding to the first pad point;

[0013] Along the first direction, the width of the third gate line is greater than the width of the first gate line body.

[0014] In some embodiments, the width of the third gate line is W. 3 , the width of the first gate line body is W 1 , W 3 and W 1 The ratio is (1.1~2):1.

[0015] In some embodiments, the first Pad point includes a first Pad point A region and a first Pad point B region connected to each other, and the first Pad point A region is closer to the edge of the back contact battery than the first Pad point B region;

[0016] Along the second direction, the length of the first Pad point A region is smaller than the length of the first Pad point B region.

[0017] In some embodiments, along the second direction, the length of the third gate line is L 3 , the length of the first Pad point A area is L 1A , the length of the first Pad point B area is L 1B , L 1A <L 3 <L 1B .

[0018] In some embodiments, the second gate line includes a second gate line body and a fourth gate line, and the second gate line body and the fourth gate line are connected as an integrated structure; along the first direction, the fourth gate line is arranged at a corresponding second pad point;

[0019] Along the first direction, the width of the fourth gate line is greater than the width of the second gate line body.

[0020] In some embodiments, the width of the fourth gate line is W. 4 , the width of the second gate line body is W 2 , W 4 and W 2 The ratio is (1.1~2):1.

[0021] In some embodiments, the second Pad point includes a second Pad point A region and a second Pad point B region connected to each other, and the second Pad point A region is closer to the edge of the back contact battery than the second Pad point B region;

[0022] Along the second direction, the length of the second Pad point A region is smaller than the length of the second Pad point B region.

[0023] In some embodiments, along the second direction, the length of the fourth gate line is L 4 , the length of the second Pad point A area is L 2A , the length of the second Pad point B area is L 2B , L 2A <L 4 <L 2B .

[0024] In some embodiments, the width of the third gate line is 50 μm to 150 μm greater than the width of the first gate line body; the width of the fourth gate line is 50 μm to 150 μm greater than the width of the second gate line body.

[0025] In some embodiments, the width of the third gate line is 80-500 μm, and the width of the first gate line body is 30-350 μm; the width of the fourth gate line is 80-500 μm, and the width of the second gate line body is 30-350 μm;

[0026] Along the second direction, the length of the third gate line is 0.5mm~3.0mm, and the length of the fourth gate line is 0.5mm~3.0mm; the length of the first Pad point A area is 0.1mm~0.45mm, and the length of the first Pad point B area is 1.0mm~5.0mm; the length of the second Pad point A area is 0.1mm~0.45mm, and the length of the second Pad point B area is 1.0mm~5.0mm.

[0027] In some embodiments, the third gate lines include at least a third gate line A and a third gate line B connected in sequence, and the third gate line A and the third gate line B have different widths.

[0028] In some embodiments, the fourth gate lines include at least a fourth gate line A and a fourth gate line B that are sequentially connected, and the fourth gate line A and the fourth gate line B have different widths.

[0029] In some embodiments, the third gate line is disposed between adjacent second gate lines, and the third gate line does not contact the second gate lines;

[0030] The fourth gate line is disposed between adjacent first gate lines, and the fourth gate line does not contact the first gate lines.

[0031] In some embodiments, a first gap is formed between the third gate line and an adjacent second gate line, and a second gap is formed between the fourth gate line and an adjacent first gate line.

[0032] In some embodiments, the width of the first gap along the first direction is W 5 , the width of the second gap along the first direction is W 6 , the width of the third gate line along the first direction is W 7 , the width of the fourth gate line along the first direction is W 8 , W 5 With W 7 The ratio is (1-2): (1-5), W 6 With W 8 The ratio is (1~2):(1~5).

[0033] In some embodiments, a third gate line is disposed between adjacent second gate lines, and the spacing between adjacent second gate lines is d 1 ;

[0034] There is no third grid line between adjacent second grid lines, and the spacing between adjacent second grid lines is d 2 ;

[0035] A fourth grid line is provided between adjacent first grid lines, and the spacing between adjacent first grid lines is d 3 ;

[0036] There is no fourth grid line between adjacent first grid lines, and the spacing between adjacent first grid lines is d 4 ;

[0037] Among them, d 2 <d 1 , d 4 <d 3 .

[0038] In some embodiments, the d 1 is 0.8~1.3mm, said d 2 0.5~1.0mm;

[0039] The d 3 is 0.8~1.3mm, said d 4 0.5~1.0mm.

[0040] In some embodiments, the area of ​​the third gate line is smaller than the area of ​​the first Pad point, and the area of ​​the fourth gate line is smaller than the area of ​​the second Pad point.

[0041] In some embodiments, the area of ​​the first Pad point is S 1, the area of ​​the second Pad point is S 2 , the area of ​​the third gate line is S 3 , the area of ​​the fourth gate line is S 4 , S 1 and S 3 The ratio is (5-10): (1-3), S 2 and S 4 The ratio is (5~10):(1~3).

[0042] In some embodiments, the width of the third gate line along the first direction is smaller than the width of the first Pad point along the first direction; the width of the fourth gate line along the first direction is smaller than the width of the second Pad point along the first direction.

[0043] In some embodiments, the third gate lines and the first Pad points are arranged along a first direction, the first Pad points are located at two ends of the back contact battery, and 1 to 10 third gate lines are arranged between the first Pad points.

[0044] In some embodiments, the fourth gate lines are alternately arranged with the third gate lines along the second direction, the fourth gate lines are arranged along the first direction, the second Pad points are located at both ends of the back contact battery, and 1 to 10 fourth gate lines are arranged between the second Pad points.

[0045] In some embodiments, the third gate line and the first Pad point and the second Pad point form a first Pad point unit; the fourth gate line and the first Pad point and the second Pad point form a second Pad point unit.

[0046] In some embodiments, the shape of the first Pad dot unit is a triangle, and the shape of the second Pad dot unit is a triangle.

[0047] In some embodiments, the shape of the first Pad point unit is an acute triangle.

[0048] In some embodiments, along the first direction, the distance between the third gate line and the first Pad point is greater than the distance between the third gate line and the second Pad point.

[0049] In some embodiments, along the second direction, the two side edges of the back side of the solar cell are provided with a first edge grid line and a second edge grid line extending along the first direction, the first edge grid line is connected to the first grid line, and the second edge grid line is connected to the second grid line;

[0050] Along the second direction, a fifth Pad point and a sixth Pad point are arranged at both ends of the solar cell sheet, the fifth Pad point is connected to the first grid line, and the fifth Pad point is connected to the first edge grid line, the sixth Pad point is connected to the second grid line, and the sixth Pad point is connected to the second edge grid line.

[0051] In some embodiments, at least one endpoint of the fifth Pad point is connected to the first edge gate line; at least one endpoint of the sixth Pad point is connected to the second edge gate line.

[0052] In some embodiments, the fifth Pad point includes a first side edge set along the first direction, and the fifth Pad point is connected to the first edge gate line through the first side edge; the sixth Pad point includes a second side edge set along the first direction, and the sixth Pad point is connected to the second edge gate line through the second side edge.

[0053] In some embodiments, the fifth Pad point is connected to 1 to 5 of the first gate lines, and the sixth Pad point is connected to 1 to 5 of the first gate lines.

[0054] In some embodiments, along the second direction, the distance between the third gate line and the fifth Pad point and / or the sixth Pad point is 2-10 mm; the distance between the third gate line and the fifth Pad point and / or the sixth Pad point is 2-10 mm.

[0055] In some embodiments, the area of ​​the first Pad point is S 1 , the area of ​​the second Pad point is S 2 , the area of ​​the third gate line is S 3 , the area of ​​the fourth gate line is S 4 , the area of ​​the fifth Pad point is S 5 , the area of ​​the sixth Pad point is S 6 , where S 5 >S 1 >S 3 , S 6 >S 2 >S 4 .

[0056] In some embodiments, the area of ​​the third gate line is S 3 , the area of ​​the fourth gate line is S 4 , the area of ​​the fifth Pad point is S 5 , the area of ​​the sixth Pad point is S 6 , S 5 and S 3 The ratio is (8~13):(1~2), S6 and S 4 The ratio is (8~13):(1~2).

[0057] In some embodiments, the first gate line and the third gate line are P-type gate lines, and the width of the P-type third gate line is greater than the width of the P-type first gate line body.

[0058] In some embodiments, the second gate line and the fourth gate line are N-type gate lines, and the width of the N-type fourth gate line is greater than the width of the N-type second gate line body.

[0059] Accordingly, the present invention also provides a back-contact battery string, comprising:

[0060] A plurality of the above-mentioned back contact batteries;

[0061] A first welding strip and a second welding strip, wherein the first welding strip is connected to the first Pad point and the third gate line, and the second welding strip is connected to the second Pad point.

[0062] In some embodiments, the second solder strip is connected to the second Pad point and the fourth gate line.

[0063] In some embodiments, the first welding strip is directly connected to the third grid line through a welding point, and the second welding strip is directly connected to the fourth grid line through a welding point.

[0064] Correspondingly, the present invention also provides a back-contact battery assembly, comprising the above-mentioned back-contact battery string.

[0065] Correspondingly, the present invention also provides a back-contact battery system, comprising the above-mentioned back-contact battery assembly.

[0066] The implementation of the present invention has the following beneficial effects:

[0067] The back contact battery and battery assembly disclosed in the present invention include first grid lines and second grid lines alternately arranged along a first direction and first pad points and second pad points alternately arranged along a second direction, wherein the first grid lines include a first grid line body and a third grid line, and the first grid line body and the third grid line are connected as an integral structure; along the first direction, the third grid line is arranged at the corresponding first pad point, and the width of the third grid line is greater than the width of the first grid line body. When welding the main grid-free back contact battery of the present invention, the welding strip is connected to the third grid line in addition to the first pad point and the second pad point, which effectively increases the welding tension of the third grid line during welding, helps to reduce and balance the welding tension on the fine grid, improves the connection reliability between the welding strip and the fine grid, avoids warping and deformation of the battery cell, and also avoids the defective rate of cracks, hidden cracks, cold solder joints, etc. during the packaging process.

[0068] In addition, when conducting electrical performance tests (such as IV tests), EL tests, and hot spot tests on back-contact batteries, the positive and negative probes of the testing device can form stable contact with the first Pad point and the second Pad point respectively, reducing the difficulty of the test and improving the test reliability and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 1 is a schematic structural diagram of a back contact battery embodiment 1 provided by the present invention;

[0070] Figure 2 yes Figure 1 A partial enlarged view of the back contact battery shown;

[0071] Figure 3 This is a schematic structural diagram of a second embodiment of a back contact battery provided by the present invention;

[0072] Figure 4 yes Figure 3 A partial enlarged view of the back contact battery shown;

[0073] Figure 5 Schematic diagram of an embodiment of a stack A of a back contact battery embodiment 3 provided by the present invention;

[0074] Figure 6 is a schematic diagram of another embodiment of the A stack of the third embodiment of the back contact battery provided by the present invention;

[0075] Figure 7 Schematic diagram of a C stacking embodiment of a back contact battery embodiment 4 provided by the present invention;

[0076] Figure 8 is a schematic diagram of another embodiment of the C stack of the back contact battery embodiment 4 provided by the present invention;

[0077] Fig. 9 1 is a schematic structural diagram of the third grid line of the fifth embodiment of the back contact battery provided by the present invention;

[0078] Fig.10 is a schematic structural diagram of the fourth grid line of the sixth embodiment of the back contact battery provided by the present invention;

[0079] Fig.11 is a schematic structural diagram of a ninth embodiment of a back contact battery provided by the present invention;

[0080] Fig.12 yes Fig.11 A partial enlarged view of the back contact battery of the present invention is shown. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0082] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0083] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0084] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in some embodiments of the present invention can be understood according to specific circumstances.

[0085] In some embodiments of the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0086] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0087] In the present invention, "preferred" and "better" are only used to describe implementation methods or embodiments with better effects, and it should be understood that they do not constitute a limitation on the scope of protection of the present invention. In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features. In the present invention, when involving numerical ranges, unless otherwise specified, the two endpoints of the numerical range are included.

[0088] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0089] The present invention provides a back-contact battery, comprising: a first gate line and a second gate line alternately arranged along a first direction; a first pad point and a second pad point alternately arranged along a second direction, the first pad point is connected to the first gate line, and the second pad point is connected to the second gate line; wherein the first gate line comprises a first gate line body and a third gate line, and the first gate line body and the third gate line are connected as an integral structure; along the first direction, the third gate line is arranged at a position corresponding to the first pad point; along the first direction, the width of the third gate line is greater than the width of the first gate line body.

[0090] When welding the main grid-free back contact battery of the present invention, the welding strip is connected to the third grid line in addition to the first pad point and the second pad point. The third grid line is a widened grid line corresponding to the first pad point, and is an integrated structure with the first grid line, which can not only improve the collection efficiency of carriers, but also serve as a welding pad during welding, effectively improving the welding tension of the third grid line during welding, which is conducive to reducing and balancing the welding tension on the fine grid, improving the connection reliability between the welding strip and the fine grid, avoiding the warping and deformation of the battery cell, and avoiding the defective rate of cracks, hidden cracks, cold welding, etc. during the packaging process.

[0091] Embodiment 1

[0092] like Figure 1 and Figure 2 As shown, a back contact battery comprises:

[0093] First gate lines 10 and second gate lines 20 are alternately arranged along a first direction;

[0094] First Pad points 30 and second Pad points 40 are alternately arranged along the second direction, wherein the first Pad points 30 are connected to the first gate line 10, and the second Pad points 40 are connected to the second gate line 20;

[0095] The first gate line 10 includes a first gate line body 11 and a third gate line 12, and the first gate line body 11 and the third gate line 12 are connected to form an integrated structure;

[0096] Along the first direction, the third gate line 12 is arranged at a position corresponding to the first pad point 30;

[0097] Along the first direction, the width of the third gate line 12 is greater than the width of the first gate line body 11 .

[0098] In this embodiment, when the main grid-free back contact battery of the present invention is welded, the welding strip is connected to the third grid line 12 in addition to the first pad point 30 and the second pad point 40. The third grid line 12 is a widened grid line corresponding to the first pad point 30. It is an integral structure with the first grid line, which can not only improve the collection efficiency of carriers, but also serve as a pad during welding, effectively improving the welding tension of the third grid line during welding, which is conducive to reducing and balancing the welding tension on the fine grid, improving the connection reliability between the welding strip and the fine grid, avoiding warping and deformation of the battery cell, and avoiding the defective rate of cracks, hidden cracks, and cold welding during the packaging process. Moreover, since the third grid line 12 is an integral structure with the first grid line, compared with ordinary pads, it can also effectively prevent the third grid line from falling off during welding, thereby improving the reliability of welding.

[0099] In addition, when conducting electrical performance tests (such as IV tests), EL tests, and hot spot tests on back-contact batteries, the positive and negative probes of the testing device can form stable contact with the first Pad point 30 and the second Pad point 40 respectively, thereby reducing the difficulty of testing and improving test reliability and stability.

[0100] It should be noted that the back contact solar cell adopts a main grid-free design, and the first grid line 10 and the second grid line 20 are fine grids, wherein the first grid line 10 is used to collect the current in the first polarity region, and the second grid line 20 is used to collect the current in the second polarity region. The polarities of the first grid line 10 and the second grid line 20 are opposite, and the polarities of the first polarity region and the second polarity region are also opposite. For example, the first grid line 10 is a positive grid line, which is used to collect the positive current in the positive region, and the second grid line 20 is a negative grid line, which is used to collect the negative current in the negative region; or, the first grid line 10 is a negative grid line, which is used to collect the negative current in the negative region, and the second grid line 20 is a positive grid line, which is used to collect the positive current in the positive region. Among them, the positive grid line is arranged in the P-type doping region of the back contact battery, and the negative grid line is arranged in the N-type doping region of the back contact battery.

[0101] The first grid line 10 and the second grid line 20 are alternately arranged, and the first grid line 10 and the second grid line 20 are both horizontal to the edge line of the back contact battery. The first grid line 10 and the second grid line 20 are alternately arranged in the vertical direction, and the first grid line 10 and the second grid line 20 are both horizontal to the upper edge line and the lower edge line of the back contact battery. The back contact battery is substantially rectangular, wherein the substantially rectangular back contact battery can be, for example, a square, or another rectangle, and can have a standard corner, a cut corner or a rounded corner, which is arranged according to actual production needs, and is not specifically limited here. At the same time, the number of the first grid line 10 and the second grid line 20 is determined according to the actual back contact battery area size, the width and distance of the first grid line 10 and the second grid line 20, and is not specifically limited here. The back contact battery can also be processed in pieces, for example, with the dotted line in the horizontal direction in the figure as the boundary, and the battery is cut.

[0102] Further, the first grid line 10 or the second grid line 20 is an aluminum grid line, a silver grid line, a copper grid line, or a silver-clad copper grid line. It is understandable that in the embodiment of the present invention, the first grid line 10 and the second grid line 20 can be selected as grid lines of the same or different metal types, for example, the first grid line 10 and the second grid line 20 are both selected from aluminum grid lines; or the first grid line 10 is selected from aluminum grid lines, and the second grid line 20 is selected from silver grid lines. Since the first grid line 10 includes a first grid line body 11 and a third grid line 12, and the first grid line body 11 and the third grid line 12 are connected as an integral structure, the third grid line 12 of the present invention is also an aluminum grid line, a silver grid line, a copper grid line, or a silver-clad copper grid line, and its material can be consistent with or inconsistent with the first grid line 10. In order to improve the collection efficiency of carriers, the material of the third grid line 12 is preferably consistent with the first grid line 10.

[0103] After welding, the welding strip of the main grid-free back contact battery expands and contracts, and an inward pulling force is generated along the second direction, which is easy to break the thin grid. The third grid line 12 is set to be a widened grid line corresponding to the first pad point 30, which can increase the welding tension and thus reduce the welding tension on the thin grid. Preferably, the width of the third grid line 12 is W 3 , the width of the first gate line body 11 is W 1 , W 3 and W 1 The ratio is (1.1-2):1, specifically 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, but not limited thereto. 3 and W 1 When the ratio is less than 1.1:1, the welding tension of the third grid line cannot be increased, and the grid line is easy to break; 3 and W 1 When the ratio of W is greater than 2.0:1, the gate line is too thick, causing light shielding loss and affecting the improvement of carrier collection efficiency. 3 and W 1 The ratio is (1.1~1.6):1.

[0104] Preferably, the width of the third gate line 12 is 50 μm to 150 μm greater than the width of the first gate line body 11 , and may be 50 μm, 70 μm, 80 μm, 90 μm, 100 μm, 120 μm, 130 μm, or 150 μm, but is not limited thereto.

[0105] Preferably, the width of the third gate line 12 is 80-500 μm, specifically 80 μm, 100 μm, 120 μm, 150 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, but not limited thereto.

[0106] The width of the first gate line body 11 is 30-350 μm, specifically 30 μm, 80 μm, 100 μm, 120 μm, 130 μm, 150 μm, 170 μm, 180 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 350 μm, but is not limited thereto.

[0107] In some embodiments, the first Pad point 30 includes a first Pad point A region 31 and a first Pad point B region 32 connected to each other, wherein the first Pad point A region 31 is closer to the edge of the back contact battery relative to the first Pad point B region 32; along the second direction, the length of the first Pad point A region 31 is less than the length of the first Pad point B region 32.

[0108] The first Pad point B area 32 can be used for testing, and can also be used as a Pad point welding ribbon, reducing process and space waste, and improving battery efficiency. The first Pad point A area 31 and the first Pad point B area 32 are different in length along the second direction, and jointly bear most of the pulling force in the second direction. The length of the third grid line along the second direction is between the first Pad point A area 31 and the first Pad point B area 32, and the pulling force on the fine grid (i.e., the first grid line body connected to the third grid line) can be reduced during welding. The present embodiment can reduce and balance the welding pulling force on the fine grid, improve the connection reliability between the welding ribbon and the fine grid, and can also ensure the convenience, reliability and stability during the tests such as electrical performance (such as IV test), EL test and hot spot.

[0109] Preferably, along the second direction, the length of the third gate line 12 is L 3 , the length of the first Pad point A area 31 is L 1A , the length of the first Pad point B area 32 is L 1B , L 1A <L 3 <L 1B .

[0110] More preferably, along the second direction, the length of the third gate line 12 is 0.5 mm to 3.0 mm, specifically 0.5 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.5 mm, 2.8 mm, or 3.0 mm, but not limited thereto.

[0111] The length of the first Pad point A area 31 is 0.1 mm to 0.45 mm, and can be specifically 0.1 mm, 0.20 mm, 0.25 mm, 0.28 mm, 0.30 mm, 0.32 mm, 0.35 mm, 0.40 mm, or 0.45 mm, but is not limited thereto.

[0112] The length of the first Pad point B area 32 is 1.0 mm to 5.0 mm, and can be specifically 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, or 5.0 mm, but is not limited thereto.

[0113] In some embodiments, the third gate line 12 is disposed between adjacent second gate lines 20, and the third gate line 12 does not contact the second gate line 20; a first gap is formed between the third gate line 12 and the adjacent second gate line 20, and the width of the first gap along the first direction is W 5 , the width of the third gate line along the first direction is W 7 , W 5 With W 7 The ratio is (1-2): (1-5). In this embodiment, by increasing the width of the third grid line and the gap between the grid line and the grid line, the connection area between the battery cells is increased under the premise of ensuring the welding tension, thereby improving the photoelectric conversion efficiency of the solar cell. At the same time, the width of the first gap should not be too small. If W 5 With W 7 If the ratio is less than 1:5, the manufacturing cost and circuit resistance will increase.

[0114] In some embodiments, the first gate line and the third gate line are preferably P-type gate lines, and the width of the P-type third gate line is greater than the width of the P-type first gate line body. Since the P-region welding reliability is low, the first gate line and the third gate line are set as P-type gate lines, which can effectively improve the welding tension of the third gate line during welding, thereby enhancing the connection reliability between the welding strip and the fine grid.

[0115] In some embodiments, the third grid line 12 and the first Pad point 30 are arranged along a first direction, the first Pad point 30 is located at both ends of the back contact battery, and 1 to 10 third grid lines 12 are arranged between the first Pad points 30. The third grid lines 12 are reasonably distributed, which comprehensively improves the welding tension of the third grid lines during welding as a whole, which is beneficial to reduce and balance the welding tension on the fine grid, and improve the connection reliability between the welding strip and the fine grid.

[0116] Embodiment 2

[0117] like Figure 3 and Figure 4 As shown, a back contact battery comprises:

[0118] First gate lines 10 and second gate lines 20 are alternately arranged along a first direction;

[0119] First Pad points 30 and second Pad points 40 are alternately arranged along the second direction, wherein the first Pad points 30 are connected to the first gate line 10, and the second Pad points 40 are connected to the second gate line 20;

[0120] The first gate line 10 includes a first gate line body 11 and a third gate line 12, and the first gate line body 11 and the third gate line 12 are connected to form an integrated structure; the second gate line 20 includes a second gate line body 21 and a fourth gate line 22, and the second gate line body 21 and the fourth gate line 22 are connected to form an integrated structure;

[0121] Along the first direction, the third gate line 12 is disposed at a position corresponding to the first pad point 30, and the fourth gate line 22 is disposed at a position corresponding to the second pad point 40;

[0122] Along the first direction, the width of the third gate line 12 is greater than the width of the first gate line body 11 , and the width of the fourth gate line 22 is greater than the width of the second gate line body 21 .

[0123] Compared with the first embodiment, in the present embodiment, the third grid line 12 is a widened grid line corresponding to the first Pad point, and the fourth grid line 22 is a widened grid line corresponding to the second Pad point. In addition to being connected to the first Pad point and the second Pad point, the welding strips of different polarities are also connected to the third grid line 12 and the fourth grid line 22. The third grid line 12 is a widened grid line corresponding to the first Pad point 30, and it is an integral structure with the first grid line; the fourth grid line 22 is a widened grid line corresponding to the second Pad point, and it is an integral structure with the second grid line, which can not only improve the collection efficiency of carriers, but also can be used as a welding pad during welding, effectively improving the welding tension of the third grid line and the fourth grid line during welding, which is conducive to reducing and balancing the welding tension on the fine grid, improving the connection reliability between the welding strip and the fine grid, avoiding warping and deformation of the battery cell, and avoiding the defective rate of cracks, hidden cracks, and cold solder joints during the packaging process. Moreover, since the third gate line 12 and the first gate line are an integrated structure, and the fourth gate line 22 and the second gate line are an integrated structure, compared with ordinary pads, the third gate line and the fourth gate line can be effectively prevented from falling off during welding, thereby improving welding reliability.

[0124] In addition, when conducting electrical performance tests (such as IV tests), EL tests, and hot spot tests on back-contact batteries, the positive and negative probes of the testing device can form stable contact with the first Pad point 30 and the second Pad point 40 respectively, thereby reducing the difficulty of testing and improving test reliability and stability.

[0125] It should be noted that the back contact solar cell adopts a main grid-free design, and the first grid line 10 and the second grid line 20 are fine grids, wherein the first grid line 10 is used to collect the current in the first polarity region, and the second grid line 20 is used to collect the current in the second polarity region. The polarities of the first grid line 10 and the second grid line 20 are opposite, and the polarities of the first polarity region and the second polarity region are also opposite. For example, the first grid line 10 is a positive grid line, which is used to collect the positive current in the positive region, and the second grid line 20 is a negative grid line, which is used to collect the negative current in the negative region; or, the first grid line 10 is a negative grid line, which is used to collect the negative current in the negative region, and the second grid line 20 is a positive grid line, which is used to collect the positive current in the positive region. Among them, the positive grid line is arranged in the P-type doping region of the back contact battery, and the negative grid line is arranged in the N-type doping region of the back contact battery.

[0126] The first grid line 10 and the second grid line 20 are alternately arranged, and the first grid line 10 and the second grid line 20 are both horizontal to the edge line of the back contact battery. The first grid line 10 and the second grid line 20 are alternately arranged in the vertical direction, and the first grid line 10 and the second grid line 20 are both horizontal to the upper edge line and the lower edge line of the back contact battery. The back contact battery is substantially rectangular, wherein the substantially rectangular back contact battery can be, for example, a square, or another rectangle, and can have a standard corner, a cut corner or a rounded corner, which is arranged according to actual production needs, and is not specifically limited here. At the same time, the number of the first grid line 10 and the second grid line 20 is determined according to the actual back contact battery area size, the width and distance of the first grid line 10 and the second grid line 20, and is not specifically limited here. The back contact battery can also be processed in pieces, for example, with the dotted line in the horizontal direction in the figure as the boundary, and the battery is cut.

[0127] Further, the first grid line 10 or the second grid line 20 is an aluminum grid line, a silver grid line, a copper grid line, or a silver-clad copper grid line. It is understandable that in the embodiment of the present invention, the first grid line 10 and the second grid line 20 can be selected as grid lines of the same or different metal types, for example, the first grid line 10 and the second grid line 20 are both selected from aluminum grid lines; or the first grid line 10 is selected from aluminum grid lines, and the second grid line 20 is selected from silver grid lines. Since the first grid line 10 includes a first grid line body 11 and a third grid line 12, and the first grid line body 11 and the third grid line 12 are connected as an integral structure, and the second grid line 20 includes a second grid line body 21 and a fourth grid line 22, and the second grid line body 21 and the fourth grid line 22 are connected as an integral structure, the third grid line 12 and the fourth grid line 22 of the present invention are also aluminum grid lines, silver grid lines, copper grid lines, or silver-clad copper grid lines, and their materials can be consistent with or inconsistent with the first grid line 10 and the second grid line 20. In order to improve the carrier collection efficiency, the material of the third gate line 12 and the fourth gate line 22 is preferably consistent with that of the first gate line 10 and the second gate line 20 .

[0128] After welding, the welding strip of the main grid-free back contact battery expands and contracts, and inward tension is generated along the second direction, which easily breaks the thin grid. The third grid line 12 is set as a widened grid line corresponding to the first pad point 30, and the fourth grid line 22 is a widened grid line corresponding to the second pad point 40, which can increase the welding tension and thus reduce the welding tension on the thin grid.

[0129] Preferably, the width of the third gate line 12 is W 3 , the width of the first gate line body 11 is W 1 , W 3 and W 1The ratio is (1.1-2):1, specifically 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, but not limited thereto. 3 and W 1 When the ratio is less than 1.1:1, the welding tension of the third grid line is not good and the grid line is easy to break; 3 and W 1 When the ratio of W is greater than 2.0:1, the gate line is too thick, causing light shielding loss and affecting the improvement of carrier collection efficiency. 3 and W 1 The ratio is (1.1~1.6):1.

[0130] The width of the fourth gate line is W 4 , the width of the second gate line body is W 2 , W 4 and W 2 The ratio is (1.1-2):1, specifically 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, but not limited thereto. 4 and W 2 When the ratio is less than 1.1:1, the welding tension of the fourth grid line is not good and the grid line is easy to break; 4 and W 2 When the ratio of W is greater than 2.0:1, the gate line is too thick, causing light shielding loss and affecting the improvement of carrier collection efficiency. 4 and W 2 The ratio is (1.1~1.6):1.

[0131] Preferably, the width of the third gate line 12 is 50 μm to 150 μm greater than the width of the first gate line body 11, and can be 50 μm, 70 μm, 80 μm, 90 μm, 100 μm, 120 μm, 130 μm, 150 μm, but not limited thereto. The width of the fourth gate line 22 is 50 μm to 150 μm greater than the width of the second gate line body 21, and can be 50 μm, 70 μm, 80 μm, 90 μm, 100 μm, 120 μm, 130 μm, 150 μm, but not limited thereto.

[0132] Preferably, the width of the third gate line 12 is 80-500 μm, specifically 80 μm, 100 μm, 120 μm, 150 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, but not limited thereto. The width of the fourth gate line 22 is 80-500 μm, specifically 80 μm, 100 μm, 120 μm, 150 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, but not limited thereto.

[0133] The width of the first gate line body 11 is 30-350 μm, and can be 30 μm, 80 μm, 100 μm, 120 μm, 130 μm, 150 μm, 170 μm, 180 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 350 μm, but not limited thereto. The width of the second gate line body 21 is 30-350 μm, and can be 30 μm, 80 μm, 100 μm, 120 μm, 130 μm, 150 μm, 170 μm, 180 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 350 μm, but not limited thereto.

[0134] In some embodiments, the first pad point 30 includes a first pad point A region 31 and a first pad point B region 32 connected to each other, the first pad point A region 31 is closer to the edge of the back contact battery than the first pad point B region 32; along the second direction, the length of the first pad point A region 31 is shorter than the length of the first pad point B region 32. The second pad point 40 includes a second pad point A region 41 and a second pad point B region 42 connected to each other, the second pad point A region 41 is closer to the edge of the back contact battery than the second pad point B region 42; along the second direction, the length of the second pad point A region 41 is shorter than the length of the second pad point B region 42.

[0135] The first Pad point B area 32 and the second Pad point B area 42 can be used for testing and can also be used as Pad point welding strips to reduce process and space waste and improve battery efficiency. The first Pad point A area 31 and the first Pad point B area 32, the second Pad point A area 41 and the second Pad point B area 42 are different in length along the second direction, and jointly bear most of the pulling force in the second direction. The length of the third grid line along the second direction is between the first Pad point A area 31 and the first Pad point B area, and the length of the fourth grid line along the second direction is between the second Pad point A area 41 and the second Pad point B area 42, which can reduce the pulling force on the fine grid (i.e., the first grid line body connected to the third grid line and the second grid line body connected to the fourth grid line) during welding.

[0136] The present invention can reduce and balance the welding tension on the fine grid and improve the connection reliability between the welding strip and the fine grid through the coordination of the first Pad point A area 31, the first Pad point B area 32 and the third gate line 12, and the coordination of the second Pad point A area 41, the second Pad point B area 42 and the fourth gate line 22, and can also ensure the convenience, reliability and stability of electrical performance (such as IV test), EL test and hot spot test.

[0137] Preferably, along the second direction, the length of the third gate line 12 is L 3 , the length of the first Pad point A area 31 is L 1A , the length of the first Pad point B area 32 is L 1B , L 1A <L 3 <L 1B The length of the fourth gate line 22 is L 4 , the length of the second Pad point A area 41 is L 2A , the length of the second Pad point B area 42 is L 2B , L 2A <L 4 <L 2B .

[0138] More preferably, along the second direction, the length of the third grid line 12 is 0.5 mm to 3.0 mm, specifically 0.5 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3.0 mm, but not limited thereto. The length of the fourth grid line 22 is 0.5 mm to 3.0 mm, specifically 0.5 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3.0 mm, but not limited thereto.

[0139] The length of the first Pad point A region 31 is 0.1 mm to 0.45 mm, and can be 0.1 mm, 0.20 mm, 0.25 mm, 0.28 mm, 0.30 mm, 0.32 mm, 0.35 mm, 0.40 mm, 0.45 mm, but is not limited thereto. The length of the second Pad point A region 41 is 0.1 mm to 0.45 mm, and can be 0.1 mm, 0.20 mm, 0.25 mm, 0.28 mm, 0.30 mm, 0.32 mm, 0.35 mm, 0.40 mm, 0.45 mm, but is not limited thereto.

[0140] The length of the first Pad point B area 32 is 1.0 mm to 5.0 mm, and can be 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, but not limited thereto. The length of the second Pad point B area 42 is 1.0 mm to 5.0 mm, and can be 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, but not limited thereto.

[0141] In some embodiments, the third gate line 12 is disposed between adjacent second gate lines 20 , and the third gate line 12 does not contact the second gate line 20 ; a first gap is formed between the third gate line 12 and the adjacent second gate line 20 , and a second gap is formed between the fourth gate line 22 and the adjacent first gate line 10 .

[0142] The width of the first gap along the first direction is W 5 , the width of the second gap along the first direction is W 6 , the width of the third gate line along the first direction is W 7 , the width of the fourth gate line along the first direction is W 8 , W 5 With W 7 The ratio is (1-2): (1-5), W 6 With W 8 The ratio is (1-2): (1-5). In this embodiment, by increasing the width of the third grid line and the gap between it and the grid line, and the width of the fourth grid line and the gap between it and the grid line, the connection area between the battery cells is increased under the premise of ensuring the welding tension, thereby improving the photoelectric conversion efficiency of the solar cell. At the same time, the width of the first gap and the second gap should not be too small. If W 5 With W 7 The ratio is less than 1:5, W 6 With W 8 If the ratio is less than 1:5, the manufacturing cost and circuit resistance will increase.

[0143] In some embodiments, the first gate line and the third gate line are preferably P-type gate lines, the width of the P-type third gate line is greater than the width of the P-type first gate line body, the second gate line and the fourth gate line are N-type gate lines, the width of the N-type fourth gate line is greater than the width of the N-type second gate line body, which can significantly enhance the connection reliability between the welding strip and the fine grid.

[0144] In some embodiments, the third grid line 12 and the first Pad point 30 are arranged along a first direction, the first Pad point 30 is located at both ends of the back contact battery, and 1 to 10 third grid lines 12 are arranged between the first Pad points 30. The third grid lines 12 are reasonably distributed, which comprehensively improves the welding tension of the third grid lines during welding as a whole, which is beneficial to reduce and balance the welding tension on the fine grid, and improve the connection reliability between the welding strip and the fine grid.

[0145] The fourth grid lines 22 and the third grid lines 12 are alternately arranged along the second direction, the fourth grid lines 22 are arranged along the first direction, the second Pad points 40 are located at both ends of the back contact battery, and 1 to 10 fourth grid lines 22 are arranged between the second Pad points 40. The fourth grid lines 22 are reasonably distributed, which comprehensively improves the welding tension of the fourth grid lines during welding as a whole, is beneficial to reduce and balance the welding tension on the fine grid, and improves the connection reliability between the welding strip and the fine grid.

[0146] Embodiment 3

[0147] Different from the first embodiment, a third gate line 12 is provided between adjacent second gate lines 20, and the distance between adjacent second gate lines provided with the third gate line 12 is d 1 There is no third gate line between adjacent second gate lines. At this time, the spacing between adjacent second gate lines without the third gate line 12 is d 2 ; where d 2 <d 1 .

[0148] Preferably, the d 1 The diameter of the d is 0.8-1.3 mm, specifically 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, but not limited thereto. 2 The thickness is 0.5 to 1.0 mm, and specifically can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm, but is not limited thereto.

[0149] The present invention sets the spacing d between adjacent second gate lines provided with the third gate line 12 to 1At this time, the first grid line body 11 becomes narrower than the third grid line 12, so that a stacked structure capable of detecting leakage contact is provided on the mixed layer below the first grid line body 11 connected to the third grid line, which can improve the leakage capacity of the solar cell and improve the reverse leakage characteristics.

[0150] like Figure 5 As shown, a first doping layer 410 is provided under the first gate line, and a second doping layer 420 is provided under the second gate line. An A stack 510 is provided on the first doping layer 410 under the first gate line body 11 connected to the third gate line 12, and the A stack 510 includes a first A stack 511, the first A stack 511 covers a partial area of ​​the first doping layer 410, and a first A spacing area 611 extending along a first direction is left on the first doping layer 410, the first A stack 511 is connected to the second doping layer 420 adjacent to the first doping layer 410, and the first A stack 511 is a doping layer, and the doping polarity of the doping layer is the same as that of the second doping layer 420.

[0151] This embodiment forms a leakage contact structure by introducing a stacked structure, and the leakage contact structure can improve the leakage capacity of the solar cell and improve the reverse leakage characteristics. In this way, as the leakage capacity is improved, at the component end, when the solar cell is blocked, the voltage at both ends of the blocked solar cell will be reduced, and the heating power of the solar cell will be reduced, thereby achieving the purpose of controlling the risk of hot spots. At the same time, the leakage contact structure has a protective effect on the hot spots caused by defects in the silicon wafer itself, which can reduce or even eliminate the requirements for defect control, and improve the manufacturing capacity of solar cells while reducing the risk of hot spots caused by defects.

[0152] Further, if Figure 6 As shown, the A stack 510 also includes a second A stack 512, which covers a partial area of ​​the first doping layer 410, and a second A spacing region 612 extending along the first direction is formed between the first A stack 511 and the second A stack 512, the first A stack 511 and the second A stack 512 are respectively connected to the second doping layer 420 adjacent to the first doping layer 410, and the first A stack 511 and the second A stack 512 are doping layers, and the doping polarity of the doping layers is the same as that of the second doping layer 420.

[0153] This embodiment introduces an A stack 510 including a first A stack 511 and a second A stack 512, wherein the first A stack 511 and the second A stack 512 cover a portion of the first doping layer 410, and the doping polarity of the first A stack 511 and the second A stack 512 is different from the doping polarity of the first doping layer 410, thereby forming a leakage contact structure, which can improve the leakage capacity of the solar cell and improve the reverse leakage characteristics. In this way, as the leakage capacity is improved, at the component end, when the solar cell is blocked, the voltage at both ends of the blocked solar cell will be reduced, and the heating power of the solar cell will be reduced, thereby achieving the purpose of controlling the risk of hot spots. At the same time, the leakage contact structure has a protective effect on the hot spots caused by defects in the silicon wafer itself, which can reduce or even cancel the requirements for the control of defects, and improve the manufacturing capacity of solar cells while reducing the risk of hot spots caused by defects.

[0154] Embodiment 4

[0155] The difference from the second embodiment is that a third gate line is provided between adjacent second gate lines, and the spacing between adjacent second gate lines provided with the third gate line is d 1 There is no third gate line between adjacent second gate lines. At this time, the spacing between adjacent second gate lines without the third gate line is d 2 A fourth grid line is provided between adjacent first grid lines, and the spacing between adjacent first grid lines provided with the fourth grid line is d 3 There is no fourth grid line between adjacent first grid lines. At this time, the spacing between adjacent first grid lines without the fourth grid line is d 4 ; where d 2 <d 1 , d 4 <d 3 .

[0156] The present invention sets the spacing d between adjacent second gate lines provided with the third gate line 12 to 1 and the spacing d between adjacent first grid lines provided with the fourth grid lines 22 3 At this time, the first grid line body 11 is narrowed relative to the third grid line 12, and the second grid line body 21 is narrowed relative to the fourth grid line 22, so that a stacked structure capable of detecting leakage contact is set on the mixed layer below the first grid line body 11 connected to the third grid line, and a stacked structure capable of detecting leakage contact is set on the mixed layer below the second grid line body 11 connected to the fourth grid line, which can improve the leakage capacity of the solar cell and improve the reverse leakage characteristics.

[0157] Preferably, the d 1The diameter of the spherical nanostructured carbon fiber is 0.8 to 1.3 mm, and specifically can be 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, or 1.3 mm, but is not limited thereto. 3 The thickness is 0.8 to 1.3 mm, and specifically can be 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, or 1.3 mm, but is not limited thereto.

[0158] The d 2 The diameter of the d is 0.5-1.0 mm, and specifically can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, but is not limited thereto. 4 The thickness is 0.5 to 1.0 mm, and specifically can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm, but is not limited thereto.

[0159] like Figure 5 As shown, a first doping layer 410 is provided under the first gate line, and a second doping layer 420 is provided under the second gate line. An A stack 510 is provided on the first doping layer 410 under the first gate line body 11 connected to the third gate line 12, and the A stack 510 includes a first A stack 511, the first A stack 511 covers a partial area of ​​the first doping layer 410, and a first A spacing area 611 extending along a first direction is left on the first doping layer 410, the first A stack 511 is connected to the second doping layer 420 adjacent to the first doping layer 410, and the first A stack 511 is a doping layer, and the doping polarity of the doping layer is the same as that of the second doping layer 420.

[0160] like Figure 7 As shown, a C stack 530 is provided on the second doping layer 420 below the second gate line body 21 connected to the fourth gate line 22, and the C stack 530 includes a first C stack 531, the first C stack 531 covers a partial area of ​​the second doping layer 420, and a first C spacing area 631 extending along the first direction is left on the second doping layer 420, the first C stack 531 is connected to the first doping layer 410 adjacent to the second doping layer 420, and the first C stack 531 is a doping layer, and the doping polarity of the doping layer is the same as that of the first doping layer 410.

[0161] This embodiment forms a leakage contact structure by introducing a stacked structure (A stack and C stack), and the leakage contact structure can improve the leakage capacity of the solar cell and improve the reverse leakage characteristics. In this way, as the leakage capacity is improved, at the component end, when the solar cell is blocked, the voltage at both ends of the blocked solar cell will be reduced, and the heating power of the solar cell will be reduced, thereby achieving the purpose of controlling the risk of hot spots. At the same time, the leakage contact structure has a protective effect on the hot spots caused by defects in the silicon wafer itself, which can reduce or even eliminate the requirements for defect control, and improve the manufacturing capacity of solar cells while reducing the risk of hot spots caused by defects.

[0162] Further, if Figure 6 As shown, the A stack 510 also includes a second A stack 512, which covers a partial area of ​​the first doping layer 410, and a second A spacing region 612 extending along the first direction is formed between the first A stack 511 and the second A stack 512, the first A stack 511 and the second A stack 512 are respectively connected to the second doping layer 420 adjacent to the first doping layer 410, and the first A stack 511 and the second A stack 512 are doping layers, and the doping polarity of the doping layers is the same as that of the second doping layer 420.

[0163] like Figure 8 As shown, the C stack 530 also includes a second C stack 532, which covers a partial area of ​​the second doping layer 420, and a second C spacing region 632 extending along the first direction is formed between the first C stack 531 and the second C stack 532, the first C stack 531 and the second C stack 532 are respectively connected to the first doping layer 410 adjacent to the second doping layer 420, and the first C stack 531 and the second C stack 532 are doping layers, and the doping polarity of the doping layers is the same as that of the first doping layer 410.

[0164] This embodiment introduces an A stack 510 including a first A stack 511 and a second A stack 512, wherein the first A stack 511 and the second A stack 512 cover a portion of the first doping layer 410, and the doping polarity of the first A stack 511 and the second A stack 512 is different from the doping polarity of the first doping layer 410, thereby forming a leakage contact structure, which can improve the leakage capacity of the solar cell and improve the reverse leakage characteristics. In this way, as the leakage capacity is improved, at the component end, when the solar cell is blocked, the voltage at both ends of the blocked solar cell will be reduced, and the heating power of the solar cell will be reduced, thereby achieving the purpose of controlling the risk of hot spots. At the same time, the leakage contact structure has a protective effect on the hot spots caused by defects in the silicon wafer itself, which can reduce or even cancel the requirements for the control of defects, and improve the manufacturing capacity of solar cells while reducing the risk of hot spots caused by defects.

[0165] This embodiment introduces a C stack 530 including a first C stack 531 and a second C stack 532, wherein the first C stack 531 and the second C stack 532 cover a portion of the second doping layer 420, and the doping polarity of the first C layer and the second C stack 532 is different from the doping polarity of the second doping layer 420, thereby forming a leakage contact structure, which can improve the leakage capacity of the solar cell and improve the reverse leakage characteristics. In this way, as the leakage capacity is improved, at the component end, when the solar cell is blocked, the voltage at both ends of the blocked solar cell will be reduced, and the heating power of the solar cell will be reduced, thereby achieving the purpose of controlling the risk of hot spots. At the same time, the leakage contact structure has a protective effect on the hot spots caused by defects in the silicon wafer itself, which can reduce or even cancel the requirements for the control of defects, and improve the manufacturing capacity of solar cells while reducing the risk of hot spots caused by defects.

[0166] Embodiment 5

[0167] like Fig. 9 As shown, different from the first embodiment, the third gate line 12 includes at least a third gate line A and a third gate line B connected in sequence, and the widths of the third gate line A and the third gate line B are different. In this embodiment, the third gate line is not a single width, but a combination of gate lines with different widths, so that different welding tensions can be matched, welding requirements under different conditions can be met, the flexibility is strong, and the connection reliability between the welding strip and the fine grid is effectively enhanced.

[0168] Embodiment 6

[0169] like Fig.10As shown, different from the second embodiment, the fourth grid line 22 includes at least a fourth grid line A and a fourth grid line B connected in sequence, and the widths of the fourth grid line A and the fourth grid line B are different. In this embodiment, the fourth grid line is not a single width, but a combination of grid lines with different widths, so that different welding tensions can be matched, welding requirements under different conditions can be met, the flexibility is strong, and the connection reliability between the welding strip and the fine grid is effectively enhanced.

[0170] Embodiment 7

[0171] Different from the second embodiment, the area of ​​the third gate line in this embodiment is smaller than the area of ​​the first Pad point, and the area of ​​the fourth gate line is smaller than the area of ​​the second Pad point.

[0172] Preferably, the area of ​​the first Pad point is S 1 , the area of ​​the second Pad point is S 2 , the area of ​​the third gate line is S 3 , the area of ​​the fourth gate line is S 4 , S 1 and S 3 The ratio is (5-10): (1-3), S 2 and S 4 The ratio is (5-10): (1-3). More preferably, S 1 and S 3 The ratio is (6-9): (1-2), S 2 and S 4 The ratio is (6~9):(1~2).

[0173] The width of the third gate line along the first direction is smaller than the width of the first Pad point along the first direction; the width of the fourth gate line along the first direction is smaller than the width of the second Pad point along the first direction.

[0174] The third grid line of this embodiment can be used to collect carriers and can also be used as a pad; the first pad point and the second pad point can be used for testing and can also be used as pad points to weld the welding strip. Therefore, this embodiment can effectively balance the relationship between welding tension, testing and carrier collection by limiting the area of ​​the third grid line and the area of ​​the first pad point, and the area of ​​the fourth grid line and the area of ​​the second pad point, so that the battery can improve both the light conversion efficiency and the reliability.

[0175] Embodiment 8

[0176] Different from the second embodiment, in this embodiment, the third gate line 12 and the first pad point 30 and the second pad point 40 form a first pad point unit; the fourth gate line 22 and the first pad point 30 and the second pad point 40 form a second pad point unit.

[0177] Preferably, the shape of the first Pad point unit is a triangle, and the shape of the second Pad point unit is a triangle. More preferably, the shape of the first Pad point unit is an acute triangle. Along the first direction, the distance between the third gate line 12 and the first Pad point 30 is greater than the distance between the third gate line 12 and the second Pad point 40.

[0178] The first gate line and the third gate line are preferably P-type gate lines, and the width of the P-type third gate line is greater than the width of the P-type first gate line body. Since the P-region welding reliability is low, the first gate line and the third gate line are set as P-type gate lines, which can effectively increase the welding tension of the third gate line during welding, thereby enhancing the connection reliability between the welding strip and the fine grid.

[0179] Moreover, since the third grid line is provided to increase the welding tension, the first Pad point can be set closer to the edge of the battery relative to the second Pad point, the distance between the third grid line and the first Pad point is greater than the distance between the third grid line and the second Pad point, and the shape of the first Pad point unit forms a triangle, which can balance the welding tension at the edge and center of the battery to avoid warping and deformation of the battery cell, and also avoid defective rates such as splitting, hidden cracks, and cold soldering during the packaging process.

[0180] Similarly, the shape of the second Pad point unit forms a triangle, which can balance the welding tension at the edge and center of the battery to avoid warping and deformation of the battery cell, and also avoid defects such as splitting, hidden cracks, and cold solder joints during the packaging process.

[0181] Embodiment 9

[0182] like Fig.11 and 12 As shown, different from the second embodiment, along the second direction, the two side edges of the back side of the solar cell are provided with a first edge grid line 13 and a second edge grid line 23 extending along the first direction, the first edge grid line 13 is connected to the first grid line 10, and the second edge grid line 23 is connected to the second grid line 20;

[0183] Along the second direction, a fifth Pad point 50 and a sixth Pad point 60 are provided at both ends of the solar cell sheet, the fifth Pad point 50 is connected to the first grid line 10, and the fifth Pad point 50 is connected to the first edge grid line 13, the sixth Pad point 60 is connected to the second grid line 20, and the sixth Pad point 60 is connected to the second edge grid line 23.

[0184] By moving the fifth Pad point 50 and the sixth Pad point 60 from the inner position of the solar cell to the first edge grid line 13 and the second edge grid line 23 respectively, and connecting them to the first edge grid line 13 and the second edge grid line 23 respectively, the distance between the Pad point and the edge grid line is shortened, thereby increasing the area of ​​PN junction formation on the solar cell, which is beneficial to improving the power of the solar cell and improving the reliability of the solar cell.

[0185] In some embodiments, at least one end point of the fifth pad point 50 is connected to the first edge grid line; at least one end point of the sixth pad point is connected to the second edge grid line. Through the connection of the end points, a path can be formed between the fifth pad point 50 and the first edge grid line 13, and between the sixth pad point 60 and the second edge grid line 23, which helps to collect current more effectively, thereby improving the photoelectric conversion performance of the cell.

[0186] In some embodiments, the fifth pad point 50 includes a first side edge arranged along the first direction, and the fifth pad point is connected to the first edge grid line through the first side edge; the sixth pad point 60 includes a second side edge arranged along the first direction, and the sixth pad point is connected to the second edge grid line through the second side edge. By connecting the first side edge and the second side edge, the contact area between the fifth pad point 50 and the first edge grid line 13 and the sixth pad point 60 and the second edge grid line 23 is increased, which can not only form a path, but also help to collect current more effectively, thereby improving the photoelectric conversion performance of the battery cell, and can also enhance the stability of the edge of the battery cell and reduce the performance degradation caused by physical loss.

[0187] Preferably, the fifth Pad point is connected to 1 to 5 of the first gate lines, and the sixth Pad point is connected to 1 to 5 of the first gate lines. By connecting to an appropriate number of gate lines, the conduction distance of the current on the first gate line or the second gate line can be reduced, effectively reducing the series resistance of the component, thereby reducing power loss and improving the fill factor and output power of the battery.

[0188] Preferably, the area of ​​the first Pad point is S 1 , the area of ​​the second Pad point is S 2 , the area of ​​the third gate line is S3 , the area of ​​the fourth gate line is S 4 , the area of ​​the fifth Pad point is S 5 , the area of ​​the sixth Pad point is S 6 , where S 5 >S 1 >S 3 , S 6 >S 2 >S 4 .

[0189] The gate line current at the edge is directly derived from the first gate line and the second gate line through the fifth Pad point and the sixth Pad point to the welding tape, thereby reducing the resistance loss, reducing the shading area and the slurry consumption, and reducing the manufacturing cost. However, the fifth Pad point and the sixth Pad point are located at the edge of the battery cell. During the manufacturing process, the welding tape also needs to cover the edge of the silicon wafer. Stress concentration may be caused during the welding of the welding tape, leading to the problem of chip cracking.

[0190] To this end, this embodiment defines the area relationship between the fifth pad point, the first pad point, and the third gate line (the areas of the fifth pad point, the first pad point, and the third gate line decrease in sequence), and the area relationship between the sixth pad point, the second pad point, and the fourth gate line (the areas of the sixth pad point, the second pad point, and the fourth gate line decrease in sequence). At the same time, the distances between the third gate line, the fourth gate line, and the fifth pad point and / or the sixth pad point are also defined.

[0191] More preferably, the area of ​​the third gate line is S 3 , the area of ​​the fourth gate line is S 4 , the area of ​​the fifth Pad point is S 5 , the area of ​​the sixth Pad point is S 6 , S 5 and S 3 The ratio is (8~13):(1~2), S 6 and S 4 The ratio of is (8-13): (1-2). Specifically, the area S of the fifth Pad point is 5 0.6mm 2 ~4mm 2 ; The area S of the sixth Pad point 6 0.6mm 2 ~4mm 2 , an exemplary area may be 1 mm 2 , 1.5mm 2 , 2mm 2 , 2.5mm 2 , 3mm 2 , 3.5mm 2, 4mm 2 If the area of ​​the fifth and sixth Pad points is too large, it will not only increase the cost, but also affect the heat dissipation of the battery cell and produce a hot spot effect.

[0192] Further, along the second direction, the distance between the third grid line and the fifth Pad point and / or the sixth Pad point is 2 to 10 mm; the distance between the third grid line and the fifth Pad point and / or the sixth Pad point is 2 to 10 mm. The third grid line can not only collect carriers, but also connect the welding strips. This embodiment limits the distance between the third grid line and the fifth Pad point and / or the sixth Pad point, which can ensure the balanced distribution of welding tension and reduce stress.

[0193] Embodiment 10

[0194] A back contact battery string, comprising:

[0195] A plurality of back-contact cells according to any one of embodiments 1 to 9;

[0196] A first welding strip and a second welding strip, wherein the first welding strip is connected to the first Pad point and the third gate line, and the second welding strip is connected to the second Pad point.

[0197] When welding the main grid-free back contact battery of the present invention, the welding strip is connected to the third grid line in addition to the first pad point and the second pad point. The third grid line is a widened grid line corresponding to the first pad point, and is an integrated structure with the first grid line, which can not only improve the collection efficiency of carriers, but also serve as a welding pad during welding, effectively improving the welding tension of the third grid line during welding, which is conducive to reducing and balancing the welding tension on the fine grid, improving the connection reliability between the welding strip and the fine grid, avoiding the warping and deformation of the battery cell, and avoiding the defective rate of cracks, hidden cracks, cold welding, etc. during the packaging process.

[0198] Preferably, the second welding strip is connected to the second pad point and the fourth grid line. The fourth grid line is a widened grid line corresponding to the second pad point, which is an integrated structure with the second grid line, which can not only improve the collection efficiency of carriers, but also serve as a welding pad during welding, effectively improving the welding tension of the fourth grid line during welding, which is conducive to reducing and balancing the welding tension on the fine grid, improving the connection reliability between the welding strip and the fine grid, avoiding warping and deformation of the battery cell, and avoiding the defective rate of cracks, hidden cracks, and cold solder joints during the packaging process.

[0199] Preferably, the first welding strip is directly connected to the third grid line via a welding point, and the second welding strip is directly connected to the fourth grid line via a welding point.

[0200] Embodiment 11

[0201] A back-contact battery assembly comprises the back-contact battery string of the tenth embodiment.

[0202] It is understandable that the solar cell assembly may further include a metal frame, a front plate, a back plate and an adhesive film, or other necessary components.

[0203] Embodiment 12

[0204] A back-contact battery system includes the back-contact battery assembly of embodiment 11.

[0205] In this embodiment, the back contact battery system can be used in photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be used in equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the back contact battery system are not limited to this, that is to say, the back contact battery system can be used in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple battery components. For example, multiple battery components can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid. After that, it is connected to the mains network to realize solar power supply.

[0206] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A back contact battery, characterized in that: include: First grid lines and second grid lines are alternately arranged along a first direction; A first Pad point and a second Pad point are alternately arranged along a second direction, wherein the first Pad point is connected to a first gate line, and the second Pad point is connected to a second gate line; Wherein, the first gate line comprises a first gate line body and a third gate line, and the first gate line body and the third gate line are connected into an integrated structure; Along the first direction, the third gate line is arranged at a position corresponding to the first pad point, and the width of the third gate line is greater than the width of the first gate line body.

2. The back contact cell according to claim 1, characterized in that The width of the third gate line is W3, the width of the first gate line body is W1, and the ratio of W3 to W1 is (1.1-2):

1.

3. The back contact cell according to claim 1, characterized in that The first Pad point includes a first Pad point A region and a first Pad point B region connected to each other, wherein the first Pad point A region is closer to the edge of the back contact battery than the first Pad point B region; Along the second direction, the length of the first Pad point A region is smaller than the length of the first Pad point B region.

4. The back contact cell according to claim 3, characterized in that Along the second direction, the length of the third gate line is L3, and the length of the first Pad point A area is L 1A , the length of the first Pad point B area is L 1B , L 1A <L3<L 1B .

5. The back contact battery according to any one of claims 1 to 4, characterized in that: The second gate line includes a second gate line body and a fourth gate line, and the second gate line body and the fourth gate line are connected as an integrated structure; along the first direction, the fourth gate line is arranged at the corresponding second pad point, and the width of the fourth gate line is greater than the width of the second gate line body.

6. The back contact cell according to claim 5, characterized in that The width of the fourth gate line is W4, the width of the second gate line body is W2, and the ratio of W4 to W2 is (1.1-2):

1.

7. The back contact cell according to claim 5, characterized in that The second Pad point includes a second Pad point A region and a second Pad point B region connected to each other, wherein the second Pad point A region is closer to an edge of the back contact battery than the second Pad point B region; Along the second direction, the length of the second Pad point A region is smaller than the length of the second Pad point B region.

8. The back contact cell according to claim 7, characterized in that Along the second direction, the length of the fourth gate line is L4, and the length of the second Pad point A area is L 2A , the length of the second Pad point B area is L 2B , L 2A <L4<L 2B .

9. The back contact cell according to claim 8, characterized in that The width of the third gate line is 50 μm to 150 μm greater than the width of the first gate line body; the width of the fourth gate line is 50 μm to 150 μm greater than the width of the second gate line body.

10. The back contact cell according to claim 9, characterized in that The width of the third gate line is 80-500 μm, and the width of the first gate line body is 30-350 μm; the width of the fourth gate line is 80-500 μm, and the width of the second gate line body is 30-350 μm; Along the second direction, the length of the third gate line is 0.5mm~3.0mm, and the length of the fourth gate line is 0.5mm~3.0mm; the length of the first Pad point A area is 0.1mm~0.45mm, and the length of the first Pad point B area is 1.0mm~5.0mm; the length of the second Pad point A area is 0.1mm~0.45mm, and the length of the second Pad point B area is 1.0mm~5.0mm.

11. The back contact cell according to claim 1, characterized in that The third gate lines at least include a third gate line A and a third gate line B which are connected in sequence, and the third gate line A and the third gate line B have different widths.

12. The back contact cell according to claim 5, characterized in that The fourth gate lines at least include a fourth gate line A and a fourth gate line B which are connected in sequence, and the fourth gate line A and the fourth gate line B have different widths.

13. The back contact cell according to claim 5, characterized in that The third gate line is arranged between adjacent second gate lines, and the third gate line does not contact the second gate lines; The fourth gate line is disposed between adjacent first gate lines, and the fourth gate line does not contact the first gate lines.

14. The back contact cell according to claim 13, characterized in that A first gap is formed between the third gate line and an adjacent second gate line, and a second gap is formed between the fourth gate line and an adjacent first gate line.

15. The back contact cell according to claim 14, characterized in that The width of the first gap along the first direction is W5, the width of the second gap along the first direction is W6, the width of the third gate line along the first direction is W7, and the width of the fourth gate line along the first direction is W8. The ratio of W5 to W7 is (1~2):(1~5), and the ratio of W6 to W8 is (1~2):(1~5).

16. The back contact cell according to claim 5, characterized in that A third grid line is provided between adjacent second grid lines, and the distance between adjacent second grid lines is d1; There is no third gate line between adjacent second gate lines, and the distance between adjacent second gate lines is d2; A fourth grid line is provided between adjacent first grid lines, and the distance between adjacent first grid lines is d3; There is no fourth grid line between adjacent first grid lines, and the distance between adjacent first grid lines is d4; Among them, d2<d1, d4<d3.

17. The back contact cell according to claim 16, characterized in that The d1 is 0.8 to 1.3 mm, and the d2 is 0.5 to 1.0 mm; The d3 is 0.8-1.3 mm, and the d4 is 0.5-1.0 mm.

18. The back contact cell according to claim 5, characterized in that The area of ​​the third gate line is smaller than the area of ​​the first Pad point, and the area of ​​the fourth gate line is smaller than the area of ​​the second Pad point.

19. The back contact cell according to claim 18, characterized in that The area of ​​the first Pad point is S1, the area of ​​the second Pad point is S2, the area of ​​the third gate line is S3, and the area of ​​the fourth gate line is S4. The ratio of S1 to S3 is (5-10): (1-3), and the ratio of S2 to S4 is (5-10): (1-3).

20. The back contact cell according to claim 5, characterized in that The width of the third gate line along the first direction is smaller than the width of the first Pad point along the first direction; the width of the fourth gate line along the first direction is smaller than the width of the second Pad point along the first direction.

21. The back contact cell according to claim 1, characterized in that The third gate lines and the first Pad points are arranged along a first direction, the first Pad points are located at two ends of the back contact battery, and 1 to 10 third gate lines are arranged between the first Pad points.

22. The back contact cell according to claim 5, characterized in that The fourth gate lines are alternately arranged with the third gate lines along the second direction, the fourth gate lines are arranged in an array along the first direction, the second Pad points are located at two ends of the back contact battery, and 1 to 10 fourth gate lines are arranged between the second Pad points.

23. The back contact cell according to claim 5, characterized in that The third gate line and the first Pad point and the second Pad point form a first Pad point unit; the fourth gate line and the first Pad point and the second Pad point form a second Pad point unit.

24. The back contact cell according to claim 23, characterized in that The shape of the first Pad dot unit is a triangle, and the shape of the second Pad dot unit is a triangle.

25. The back contact cell according to claim 24, characterized in that The shape of the first Pad point unit is an acute triangle.

26. The back contact cell according to claim 23, characterized in that Along the first direction, the distance between the third gate line and the first Pad point is greater than the distance between the third gate line and the second Pad point.

27. The back contact cell according to claim 5, characterized in that Along the second direction, the two side edges of the back side of the solar cell are provided with a first edge grid line and a second edge grid line extending along the first direction, the first edge grid line is connected to the first grid line, and the second edge grid line is connected to the second grid line; Along the second direction, a fifth Pad point and a sixth Pad point are arranged at both ends of the solar cell sheet, the fifth Pad point is connected to the first grid line, and the fifth Pad point is connected to the first edge grid line, the sixth Pad point is connected to the second grid line, and the sixth Pad point is connected to the second edge grid line.

28. The back contact cell according to claim 27, characterized in that At least one endpoint of the fifth Pad point is connected to the first edge gate line; at least one endpoint of the sixth Pad point is connected to the second edge gate line.

29. The back contact cell according to claim 27, characterized in that The fifth Pad point includes a first side edge arranged along the first direction, and the fifth Pad point is connected to the first edge gate line through the first side edge; the sixth Pad point includes a second side edge arranged along the first direction, and the sixth Pad point is connected to the second edge gate line through the second side edge.

30. The back contact cell according to claim 27, characterized in that The fifth Pad point is connected to 1 to 5 of the first gate lines, and the sixth Pad point is connected to 1 to 5 of the first gate lines.

31. The back contact cell according to claim 27, characterized in that Along the second direction, the distance between the third grid line and the fifth Pad point and / or the sixth Pad point is 2-10 mm; the distance between the fourth grid line and the fifth Pad point and / or the sixth Pad point is 2-10 mm.

32. The back contact cell according to claim 27, characterized in that The area of ​​the first Pad point is S1, the area of ​​the second Pad point is S2, the area of ​​the third gate line is S3, the area of ​​the fourth gate line is S4, the area of ​​the fifth Pad point is S5, and the area of ​​the sixth Pad point is S6, wherein S5>S1>S3, S6>S2>S4.

33. The back contact cell according to claim 32, characterized in that The area of ​​the third gate line is S3, the area of ​​the fourth gate line is S4, the area of ​​the fifth Pad point is S5, and the area of ​​the sixth Pad point is S6. The ratio of S5 to S3 is (8-13):(1-2), and the ratio of S6 to S4 is (8-13):(1-2).

34. The back contact cell according to claim 1, characterized in that The first gate line and the third gate line are P-type gate lines, and the width of the P-type third gate line is greater than the width of the P-type first gate line body.

35. The back contact cell according to claim 5, characterized in that The second gate line and the fourth gate line are N-type gate lines, and the width of the N-type fourth gate line is greater than the width of the N-type second gate line body.

36. A back contact battery string, characterized in that: include: A plurality of back contact cells according to any one of claims 1 to 35; A first welding strip and a second welding strip, wherein the first welding strip is connected to the first Pad point and the third gate line, and the second welding strip is connected to the second Pad point.

37. The back contact cell string according to claim 36, characterized in that The second soldering strip is connected to the second Pad point and the fourth gate line.

38. The back contact cell string according to claim 37, characterized in that The first welding strip is directly connected to the third grid line through a welding point, and the second welding strip is directly connected to the fourth grid line through a welding point.

39. A back contact battery assembly, characterized in that: Comprising a back-contact battery string as described in any one of claims 36 to 38.

40. A back contact battery system, characterized in that: Comprising a back contact battery assembly as described in claim 39.

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